1. Field of the Invention
This invention relates to an apparatus for sewage purifying treatment by improving the dissolving efficiency of oxygen. This is accomplished by jetting into sewage a pressurized water current and micronized bubbles made by the synergistic effect of the pressurized water current and air current which is introduced as it is spiralling from the outer circumferential part of the pressurized water current.
2. Description of Prior Art
Conventionally, drainage chiefly from households, dead leaves and other organic substance flow into enclosed water areas, such as culture ponds, reservoirs, scenic ponds provided at parks, golf courses, etc. or open water areas, such as rivers, ports and harbors. Such inflows stagnate, become rotten and emit offensive odors, causing malodor pollution to nearby residents. Moreover, water quality deteriorates because of substances which flow in and stagnates, with the resultant growth of water-bloom or the like. In the case of culture ponds, it is important to aim at purification of water quality so as to prevent fish disease, promote growth of cultured fish and improve quality of such fish. In the case of agricultural reservoirs, it has been ascertained that deterioration of water quality adversely affects growth of the crops.
The conventional method of purifying the water quality of culture ponds, scenic ponds, rivers, etc., is to use the jet type aeration system, an agitation system whereby an agitator is provided on the surface of a pond to agitate the surface of the water to bring both the water and air into contact and an air blowing system whereby air flows into the water so as to form micro-bubbles. All of these systems aim at improving of the dissolved oxygen content.
In the case of the conventional water agitating and aerating machine, however, a screw is arranged on the surface or below the surface of the water for supplying and mixing the air into the water. According to this conventional machine, it is possible to agitate and aerate the waste water on the surface part but it is difficult to agitate and aerate the waste which is below the surface or which is away from an agitator. Moreover, it is impossible for this machine to purify sludge sedimented on the bottom of a pond or the like. Thus, there is a limit in the range and ability of agitation and aeration for the conventional machine.
Since the conventional machine has a mechanically driven part which is to be set under the surface of the water or at the place which is subject to infiltration of the water, such driven part easily wears or mechanically fails due to impurities contained in the water. Thus, periodical inspection and maintenance are required.
It has been known that in the case of forming air taken in the water into bubbles, the more the bubbles are micronized, the more the dissolved oxygen content is improved. However, in the method of agitating the water and forming bubbles by revolution of a screw, there is a limit in the micronization of bubbles and increased power is required. In particular, a commercial power source equipment is required on the spot.
In the case of the air suction method, when the aeration is stopped impurities penetrate into the nozzle which is always under water due to water pressure and consequently the nozzle is clogged. Thus, repetition of aeration operations and stoppage can cause clogging of the nozzle and reduces the aeration effect.
In the case of stock farmers, the sewage purifying treatment apparatus of conventional type is too expensive and it is customary to store animal waste from livestock (pigs, cows, etc.) temporarily in sewage reservoirs dugout and then spread animal waste over a field or the like periodically. However, spreading of such unfermented animal waste is not suitable for growth of agricultural products and it is required to leave fields as they are until animal waste ferments to such an extent that it can be absorbed by plants in fields as fertilizer. Moreover, offensive odors emitted from sewage reservoirs and from spread waste cause the pollution problem.